The Australian Telecommunications Industry Ombudsman (TIO) has recorded a 2 percent decrease in the total number of complaints in the last financial year, but customer complaints about mobile phones have risen by 9 percent.

There were a total of 193,702 complaints in the 2011-12 financial year, with 122,834 of these complaints relating to mobile phones.

Ombudsman Simon Cohen noted that the last quarter of the last financial year was the TIO's "quietest in almost two years."

"This is a positive sign that reflects the focus by a number of telcos on improving their customer service," he said.

The biggest complaints relating to mobile phone services were about poor coverage and billing disputes.

The TIO received 15,752 complaints about inadequate spend-management tools, 13,943 complaints about disputes with billing, 10,556 disputes about internet charges, and 4,186 complaints about roaming charges.

Cohen said that the billing-dispute complaints show the need for adequate spend-management tools, which are now included as part of the industry's Telecommunications Consumer Protection (TCP) code. The major telecommunications providers, Telstra, Optus, and Vodafone, now alert customers when they are nearing their monthly data limits on mobile plans, for example.

"I'm very hopeful that the new TCP code will reduce the need for consumers to come to the TIO," he said in a press conference this morning.

New South Wales recorded the greatest number of complaints — but on a population basis, Victoria won out, with 10.6 complaints per 1,000 people. Northern Territory customers complained the least, with just 5.5 complaints per 1,000 people.

Melbourne CBD recorded the most complaints per 1,000 people, with the top complaints relating to bill shock or disputed charges.